Phonographic apparatus and method therefor



E. GRISSINGER PHCNOGRAPHIG APPARATUS AND METHOD THEREFOR Filed May 2'7,1918 Patented I Oct. 26 1926.

. UNITED STATES PATENT OFFICE.

ELW 00D GRISSINGER, 0F BUFFALO, NEW YORK, ASSIGNOR TO LUOY ASHGBISSINGER,

' OF BUFFALO, NEW YORK.

PHONOGRAP HIO APPARATUS AND METHOD THEREFOR.

Application filed May 27, 1818. Serial No. 288,734.

My present invention .is shown as embodied in phonographic apparatuswhich is primarily adapted for recording sound upon a wax or otherimpressionable surface. An important object of my invention is toinsi'ire faithful translation of speech waves or other variations havingsimilar frequencies or similar complexities, into correspondinglyvarying movements of a lever or other machine element. The specificpurpose in view is utilizing the said physical movements formechanically tracing or cutting an outline or profile having physicalinequalities corresponding faithfully to the original speech vibrations,but certain features of my invention which contribute to this object arecapable of useful employment in other instruments wherein faithfulexecution of complex or high frequency waves or movements is necessaryor desirable.

In phonographic work, whether recording or reproducing, the widelyvarying frequencies'as also the complexities of speech waves, should berepresented only by the rapidly varying rates of speed and frequency ofsimple to-and-fro physical movements of the vibratory system,.and tosecure more faithful response toand transmission of such waves, the tonearm or lever should execute and transmit the physical movementscorrespending .to each and all of the component frequencies with equalefliciency and without disproportionately amplifying or diminishing anyof them. In my companion aplication of even date herewith, issued asatent No. 1,480,203, Jan. 8, 1924, Iv have shown and described meanswhereby disroportionate am lifying may be avoided y constructing t evibratory system so as not to have an pronounced natural frequenciescorrespon ing to the important frequencies of speech.- This is effectedby predetermining the weight, stiffness and elasticity of the vibratorysystem so that it will have a single natural frequency lower than any ofsaid speech frequencies, and so that the natural frequencies of theelastic elements being too high and of too small total energy to benoticeable in the re roduced sounds. In said application, I ave alsoshown how damping may be limited mainly to factors WhlCh will operatesubstantially equally with reference to all of the frequencies involved.These features are of peculiar advantage and novelty for the practiceof'55 my present invention for the reasons ex plained below and may beproperly claimed in combination therewith, but my present inventionconcerns more particularly another damping factor which is phonographicrecording.

According to present practice, the stylus used for cut-ting the waxrecord from which the master record is made is caused to mold or cut aspiral groove in the wax, external 5 power being applied throughsuitable mechanism to produce such movement and trace such grooveindependently of the energy of the sound waves. The sound waves,however, are required to do all of the work of vibrating the stylustransversely of the spiral groove to produce the sound wave record. Thesound waves impinge directly upon a diaphragm, the to-and-fro movementsof the diaphragm force corresponding 7 movements of one end of a pivotedlever and the other end of the ievei' carrying the sharpened stylusmolds or cuts corresponding physical undulations in said spiral groove.These undulations, whether lateral as in the Victor talking machine, orvertical,v as in the Edison phonograph, constitute the record of theoriginal sound. The fidelity of the record and of the sound to be repro-.duced therefrom, will depend upon how accurately the movements of thesharpened point reproduce the changes of frequency and amplitude of thesound waves impinging upon the diaphragm.

The recording operation is not materially v different where themovements of the stylus lever are caused by telephonic waves acting onan armature instead of airwaves acting on a diaphragm. In either casethe wave energies are elastically or non-positively applied and theamplitudes and velocities of transverse movement which they can impartto the stylus will be limited and modified by the nature and extent ofthe various oppositions or resistances (damping facpeculiar to 60 tors)which oppose the transverse 'movements. hese damping factors include thefrictional and other resistances to transverse cutting or molding of thematerial of the record by the stylus.

The friction is considerable because considerable pressure, usually adead-weight or gravity pressure, is necessary to maintain the stylus inintimate engagement with the wax or other impressionable material. Forthe same a'eason the spiral groove is necessarily of considerable depthand the work to be done in transversely molding or cutting the materialof the groove is correspondingly great.

These damping factors operating in opposition to all transversevibrations of the lever have different values for different frequencies,velocities and amplitudes of the transverse movement. Consequently, thiskind of damping distorts some frequencies and obliterates others,particularly the overtones or high frequency components of complexwaves. As aresult, the tone pitch is greatly modified, the quality ofthe sound is not faithfullyreproduced and nasal or metallic sounds andnoise effects become objectionably prominent.

My present invention contemplates decreasing the above descr'ibed eHectsof damping by putting the stylus in a state of continuous rapidvibration transversely of the spiral groove,by energy derived from asource independent of the sound waves to be recorded. The outside energydoes the work of overcoming transverse friction, and of transversemolding or cutting of the groove. -This being the normal continuousoperation of the apparatus, the work to be done by the sound waves willbe merely that of shifting the field of the transverse molding orcutting operation which is being independently maintained by the outsidesource of power. As a result, the transverse shifting due to the soundenergy will be proportionally greater for all frequencies involved, andthat due to the minute energy of the overtones and high frequencycomponents will be more nearly proportional to the energies thereof,instead of being disproport'ionally damped out as in prior practice.Hence such nasal and other disagreeable sounds and noise effects as aredue to unfaithful distorted recording are eliminated. but the methodbeing essentially one of faithful recording of any and all appliedenergy which reaches the stylus, it necessarily follows that noises anddisturbances whether externally or internally originated, are alsofaithfully recorded on V the record.

The continuous transverse vibration referred to must be uniform and therate of vibration such that the sound waves reproduced therefrom willnot impair the quality or character of the sound waves to be recorded.The auxiliary energy suitable for this purpose may be a high frequencyalternating current of pure tone quality, having a periodicitypreferably somewhatin excess of 10,000 periods per second. The amount.of this energy, though small may be and preferably will be greater thanthe energy of the sound waves to be recorded.

The frequency of the auxiliary energy may be varied within quite widelimits. The principal resonant frequencies of the vowel sounds are below1,000 periods per second. Sound waves in air are seldom distinguishableabove 16,000 periods per second and the louder components are below5,000 per second. This is particularly true of sound waves coming fromthe megaphone or horn of a phonograph. W'hile frequencies of 8,000 to10,000 periods or more may be employed, the requirement is only that theperiodicity be such that-when recorded and reproduced, it will notevidence itself as a predominant or objectionable tone.

The frequency may be well Within the recognized limit of audibility butif it is a perfectly uniform tone and not of too great volume, it is notnecessarily objectionable. The ear very quickly becomes adjusted to sucha condition and a pure continuous tone will pass unnoticed. In certaincases. I take advantage of this fact to employ a frequency and amplitudewhich will give a tone, which though very noticeable when the attentionis directed to it, is ordinarily unnoticed. Such a tone may serve as ahighly desirable substitute for the intermittent or non-uniform scratchytones and metallic qualities which in prior devices frequently causeannoyance to the hearer.

Alternating current generators useful for my purpose'have been designedand constructed giving frequencies much above 30,000 "pulsations persecond. Moreover, they have pure tone, that is, sine wave 110 forms.Transformers, electromagnets and armatures forsuch high frequencies arealso well known and may be employed. The practical difficulties and theexpense will be less, however, and the phonographic re- 115 sults notprohibitively inferior, where frequencies of 10,000 to 7,000 or evenlower, are employed or Where vacuum tube or other frequency changers areused in place of the special alternating generators.

Imparting to the vibratory system continuous vibrations of even thelowest of the above frequencies will have a tendency toexcite all partsof the system to local or segmental vibrations and to develop and 125magnify rattles and other noise-generating activities atfevery. weakpoint in the system; hence the advantage and invention involved inutilizing for practice of my present invention the noise-free vibratorysystem such as disclosed in my said companion application. While avibratory system of the structure herein disclosed embodies the requiredqualities in a desired form, it is evident that specificall difi'erentconstructions may be devised havlng the same qualities.

The apparatus and also the method constituting my present invention maybe more fully understood from the following description in connectionwith the accompanying drawings, inwhich-- Figure 1 is a face view of asound box adapted to be used as a recorder for the practice of mypresent invention;

Figure 2 is a vertical central section showing a simple embodiment of myinvention;

igure 3 is a similar section showing a modification; and

' herewith. Such construction may be easily Figure 4 is a detailed viewshowing the rear end of the magnet coil casing.

In these drawings the sound box comprises the annular ring 1, formedwith the inwardly projecting annular flange 2 and back-plate 3. In therecess between flange '2 and plate 3 is clamped the diaphragm 5 of micaor other suitable materia disposed between a pair of rubber cushioningrings 6'.

The annular ring2 is formed on one side with an enlargement 7 adapted toform a solid base support for the mounting of the stylus lever 11. Theback-plate 3 is formed with an annular opening 8 through which may beapplied the energy of the sound waves to be recorded.

The lever arm 11 is attached to the diaphragm near, although notnecessarily at the center thereof, and the op osite end is provided witha cutting or mol ing point 14, which may be of any known or desired formand which ma be detachably secured in socket 12 by bmdin screw 13. Thelever 11, may be of any own ordesired construction but is preferably ofan aluminum alloy and the long arm may be made light yet very rigid bygiving it the ribbed construction indicated in the drawings. The pivotalmounting of the lever may be of any approved construction but as showncomprises two wires 15, 16, preferably steel piano wires. These wiresare fixed attheir ends, as for instance by clamps 17, 18 and deflectingposts 19, 20, 21, 22, and are spread apart at their intermediateportions where they engage the lever. The two wires may be symmetricallydisposed with respect to the pivotal axis and with respect to thelongitudinal axis of the lever and may be stretched to very high tensionprevious to clamping, as and for the purposes explained in my companionapplication of even date organized and adjusted so as to have no naturalfrequencies within .therange of the important frequencies of speech, thefundamental being of course below and the frequencies of theelastic wireabove said range, as explained in my companion application.

While the above described construction of sound box, lever and pivotalmounting are highly desirable for my resent purpose, it will beunderstood that t e broad principle of my present apparatus and methodof operation are applicable to any known construction of phonographicrecorder or annalogous instrument.

In Figure 2 m invention is shown as applied to a soundliox adapted torecord air sound waves directly, that is, the sound waves travelingthrough the air are collected by a suitable mouth-piece 10, arepropagated through passage 8 and impinge directly on apply the vibratoryenergy in direct alignment with the sound wave energy applied by thediaphragm. In this case the auxiliary energy is that of an alternatingcurrent app led throu h an electromagnet. The outer end of ro 22 isformed or provided with a soft iron armature 23, which may be detachablyor adjustabl screwthreaded thereon as indicated in igure 2. This softiron armature projects into a solenoid and closely confronts a polepiece 24 at a point near the center of the solenoid and therefore in themost sensitive part of the field thereof.

The electromagnet is mounted on a supplemental casing 25 and comprises asoft iron shell 26. This shell is slotted as indicated at 27 Figure 4,and is rigidly secured to 25 by an integral flange 28 and the screws 29.The pole piece 24 is screw-threaded in the end of shell 26 so as to bemechanically adjustable inwardly or outwardly and it is adapted to beheld in fixed position after adjustment by the lock nut 30.

Within the shell 26 are the solenoid windings for applying the highfrequency current for variably magnetizing the pole piece 24 to impartthe desired continuous vibratory movement to the armature 23 and throughit to the stylus lever 11. These coils areclosed in at the end by theremovable annulus 51 which is of magnetic material so as to concentratethe magnetic field close to armature 23. The inner cylinder 52 is ofnon-magnetic material so as not to short circuit the magnetic field.

One of these windings as 31 is connected to the high frequency source ofenergy, diagrammatically indicated as an alternating current generator32, through wires 33, 34 which-preferably include an adjustableresistance 35 whereby the amount of the alternating current andresulting amplitude of vibration of the stylus may be regulated tosecure the results hereinabove described.

The high frequency energy though derived from an alternating source ispreferably employed so as not to cause reversing magnetism of theelectromagnet but only single polarity pulsations of increasing anddecreasing magnetism. This may be accomplished by applying, preferablythrough a separate winding 36, a continuous direct current of suliicientpower to keep the magnet continually polarized in one direction.

For this purpose, the winding 36 may be connected through wires 37, 38and an adj ustable resistance 39 with a source of direct current as forinstance the battery 40.

By suitably adjusting the resistance 39 which controls theuni-directional magnetizing current in coil 36 and separately adjustingthe resistance 35, which controls the alternating energy in coil 31, theinitial attraction of the pole piece 24 for armature 22, as well as theamount of the variation of such attraction, may be made of just thestrengths required for giving the best results. The constant initialpull of the magnet upon the armature may be balanced by adjusting thelever 11 along the rod 22 to vary the initial tension of the pivotalwires 15, 16. This tension may be assisted or opposed by buckling of thediaphragm 4 either toward or away from the lever 11.

lVhen the high frequency current traverses its coil 31, the attractionbetween thearmature 23 and the pole piece 24 is varied in accordancewith the wave form and frequency of the alternating current and theopposing spring tension remaining constant, the armature 23 and styluslever 11, are correspondingly vibrated. Sound waves entering thecollecting horn 10 and impinging on the diaphragm merely modify thismovement and the wave forms recorded on the wax platen will be acomposite of the continuously maintained high frequency vibration andthecomplex sound wave vibrations superposed. i

In Figure 3 a simple form of an-all electric recorder is shown. Allparts remain the same as before except that the horn for collect ngsound waves from the air has been removed and the coils and shell 26 aresubstituted in its place. The connection of coil 31 to the highfrequency alternating source 35 and the connections of coil 36 to thebattery through the resistance 39 may be the same as in Figure 2. Thediaphragm, however, no longer serves as the means for applying the soundwaves to the lever, its only function being that of an end support andguide for the lever 11 and the armature 23. The waves to be recorded areelectrically superposed on the continuous high frequency currentproducing a composite electric wave form in coil 31 whichelectromagnetically imparts a correspondingly varying physical movementto armature 23 and stylus lever 11.

Where the waves to be recorded are acoustic air waves they aretranslated into corresponding electrical waves through the medium of atelephone transmitter diagrammatically indicated at 41. The air wavesvibrate the transmitter diaphragm thus varying the resistance of amicrophone, and correspondingly varying the continuous current frombattery 40 by and in accordance with the undulations of the originalsound waves. The resulting electrical or telephonic waves aretransferred through induction coil 43 which may be arranged in paral lelwith the high frequency generator 32 and connected to the magnetcoil 31through the same wires 33, 34.

The telephone transmitter is preferably of the type shown in my priorPatent No. 1,198,345, granted September 12th, 1916, and the currentsreceived therein may be amplified by telephonic repeaters of the typeshown in my prior Patents Nos. 1,198,213, 1,203,326 or 1,205,618.

WVhile I have shown and described a desirable embodiment of myinvention, including a special construction of sound box and specialmeans for giving the stylus lever the desired continuous vibration atthe desired high frequency, it will be understood that my invention is abroad one and various changes, substitutions, omissions andadditions'may be made without departing from the spirit of my invention.

I claim:

1. In a phonographic sound box and in combination with the vibratorylever thereof, means for superposing on the phonographic movements ofthe latter an additional continuous musical vibration of such frequencand amplitude as will not produce ob ectionable effects in the resultantphonographic sound product, said means including an armature on saidlever, an electromagnet in operative relation thereto and sources ofalternating current and direct current for simultaneously energizingsaid electromagnet.

2. In a phonographic sound box and in combination with. the vibratorylever thereof, means for superposing on the phonographic movements ofthe latter an additional continuous musical vibration of such frequencyand amplitude as will not produce objectionable effects in the resultantphonographic sound product, said means including an armature on saidlever, a continuously polarized magnet in operative re- 7 highfrequencyto-and-fro movement in a single plane and means for elasticallyor non-positively applying complex or high frequency wave energy tocause correspond.-

ing movements of said element in said plane,

in combination-with means including a polarized electromagnet and analternating current generator for continuously applying uni-directionalpulsations for vibrating said element to and fro in said plane at afrequency above 10,000 pulsations per second.

4. In a phonographic apparatus and in combination with the stylusleverthereof, means for vibrating said lever including a magneticpole-piece rigidly secured thereto, a solenoid electromagnet providedwith an axial pole-piece extending approximately to the center thereofand closely confronting said first mentioned pole-piece, together withmeans for energizing said electromagnet, said means including analternating current generator of frequency higher than the importantfrequencies of speech.

.5. In a phonographic apparatus and in combination with the stylus leverthereof, means for vibrating said; lever including a magnetic polepiecerigidly secured thereto, a solenoid electromagnet provided with an axialpolepiece extending approximately to the center thereof and closelyconfronting said first mentioned pole-piece, together with means forenergizing said electromagnet, said means including a high frequencygenerator, a batteryand a telephonic circuit. 6. In a phonographapparatus and in combination with the stylus lever thereof, means forvibrating said lever includingan'armature in the form of a solenoidalcore-piece rigidly secured thereto, an iron clad solenoid magnetprovided With a pole-piece extending approximately to the center thereofand closely confronting said first mentioned pole-piece, together withmeans for energizing said electromagnet, said means including atelephonic transmitter.

Signed at New York city in the county .of New York, and State of NewYork, this 25th day of May, A. D. 1918.

. ELWOOD GRISSINGER.

